A radial mandrel or winding drum for the manufacture of tires, laminated products, bands or coils is cylindrical in configuration and mounted for rotation. Piles of the material, such as uncured rubber in the case of tire building, are wrapped about the mandrel to form a carcass. The carcass is thereafter removed from the mandrel for further processing.
A typical radial mandrel or winding drum is made up of a plurality of alternate large and small segments having alternate large and small arcuate shells on their outer surfaces. A detailed discussion of a winding drum in which such structural features and their operation are described is provided in U.S. Pat. No. 3,375,154, which is particularly directed to a tire building drum. As in similar tire building drums, the segments of the '154 patent are adapted to be expanded radially until the shells form a substantially perfect cylinder on which the carcass is formed. Upon completion of the winding operation, the segments are adapted to be contracted so as to pull the shells away from the tire carcass and enable the carcass to be easily removed from the drum.
There are several variations in the prior art for expanding and contracting the segments of the mandrel or drum during a complete winding operation for a tire or other object. The apparatus shown in the '154 patent includes a threaded shaft arrangement whose threads are reversed at each end so that rotation in one direction causes threaded members disposed on each end to move axially toward one another and rotation in the opposite direction causes such members to move axially outwardly from each other. The large and small segments communicate with such members to move radially inwardly and outwardly as such members move toward and away from one another. Although this shaft configuration provides a workable mechanism for expanding and contracting the large and small segments of such winding drums, it can be appreciated that machining a shaft whose threads are reversed at each end is relatively costly. In addition, a shaft of such specialized design may not be readily retrofitted or substituted for similar structure in other radial mandrel or winding drum designs.
It has therefore been an object of this invention to provide a mechanism for expanding and contracting the segments and shells of a radial mandrel or winding drum, which mechanism is relatively simple in construction and may be readily adapted with radial mandrels and winding drums of various designs.
It is another object of this invention to provide a mechanism for expanding and contracting a radial mandrel or winding drum which can be adapted for use with a standard drive shaft.